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熊梓言 《测绘与空间地理信息》2008,31(4)
GPS(Global Positioning System)全球定位系统是美国研制并在1994年投入使用的卫星导航与定位系统.其应用技术已遍及国民经济的各个领域.在测量领域,GPS系统已广泛用于大地测量、工程测量、航空测量以及地形测量等各个方面.本文将以双鸭山市的省公路路网项目为例,概略叙述GPS系统在公路工程控制测量中的应用. 相似文献
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以3种目前在测绘行业较为常用的GPS(global positioning system)数据处理软件为研究对象,选取了某项目中10条不同长度的GPS静态测量基线数据,对比分析了这三款软件在基线处理和网平差结果中的差异及精度,为工程测量中的用户选取合适的数据处理软件提供参考和依据。 相似文献
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Recent studies have shown the capabilities of Global Positioning System (GPS) carrier phases for frequency transfer based
on the observations from geodetic GPS receivers driven by stable atomic clocks. This kind of receiver configuration is the
kind primarily used within the framework of the International GPS Service (IGS). The International GPS Service/Bureau International
des Poids et Mesures (IGS/BIPM) pilot project aims at taking advantage of these GPS receivers to enlarge the network of Time
Laboratories contributing to the realization of the International Atomic Time (TAI).
In this article, we outline the theory necessary to describe the abilities and limitations of time and frequency transfer
using the GPS code and carrier phase observations. We report on several onsite tests and evaluate the present setup of our
12-channel IGS receiver (BRUS), which uses a hydrogen maser as an external frequency reference, to contribute to the IGS/BIPM
pilot project.
In the initial experimental setup, the receivers had a common external frequency reference; in the second setup, separate
external frequency references were used. Independent external clock monitoring provided the necessary information to validate
the results. Using two receivers with a common frequency reference and connected to the same antenna, a zero baseline, we
were able to use the carrier phase data to derive a frequency stability of 6 × 10−16 for averaging times of one day. The main limitation in the technique originates from small ambient temperature variations
of a few degrees Celsius. While these temperature variations have no effect on the functioning of the GPS receiver within
the IGS network, they reduce the capacities of the frequency transfer results based on the carrier phase data. We demonstrate
that the synchronization offset at the initial measurement epoch can be estimated from a combined use of the code and carrier
phase observations. In our test, the discontinuity between two consecutive days was about 140 ps. ? 1999 John Wiley & Sons,
Inc. 相似文献
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包头市郊区土地资源动态监测中的GPS应用 总被引：3，自引：0，他引：3
结合国家“九五”重点课题及在包头市郊区的实验,介绍了全球定位系统的定位原理和特点,阐述了包头市郊区土地资源动态监测工作中的GPS选型思路、基准站建立方法、外业数据采集方法、外业测量记录内容和GPS数据的内业处理过程等关键环节。 相似文献
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一个新的GLONASS与GPS的坐标转换关系 总被引：3，自引：0，他引：3
介绍了一组新的更精确的PZ-90与WGS-84两种坐标框架之间转换参数。其中详细描述了其转换参数的求解模型和实验方案，对求解的转换参数进行了分析。 相似文献
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哈尔滨市树木管理信息系统突破了以往以城市市区美化、绿化为目标的狭义的城市园林或绿化的管理,而是为维护城市生态环境系统服务的体系。“3S”技术(GIS—地理信息系统、RS—遥感、GPS—全球定位系统)、网络技术、多媒体技术、数据库技术为哈尔滨市树木管理信息系统提供了技术支持。哈尔滨市树木管理信息系统的建设和应用,在政府各相关部门进行重要项目论证和重大问题决策方面将提供详实、准确的依据。 相似文献
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GEODESY AND DIGITAL CARTOGRAPHIC SURVEY IN FILDES PENINSULA,REY JORGE ISLAND,ANTARCTICA 总被引：1，自引：0，他引：1
Jürgen Klotz 《地球空间信息科学学报》2001,4(2):25-31
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The Global Positioning System (GPS) satellite differential code bias (DCB) should be precisely calibrated when obtaining ionospheric slant total electron content (TEC). So far, it is ground-based GPS observations that have been used to estimate GPS satellite DCB. With the increased Low Earth Orbit (LEO) missions in the near future, the real-time satellite DCB estimation is a crucial factor in real-time LEO GPS data applications. One alternative way is estimating GPS DCB based on the LEO observations themselves, instead of using ground observations. We propose an approach to estimate the satellite DCB based on Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) and Challenging Minisatellite Payload (CHAMP) GPS observations during the years 2002–2012. The results have been validated through comparisons with those issued by Center for Orbit Determination in Europe (CODE). The evaluations indicate that: The approach can estimate satellite DCB in a reasonable way; the DCB estimated based on CHAMP observations is much better than those on COSMIC observations; the accuracy and precision of DCB show a possible dependency on the ionospheric ionization level. This method is significance for the real-time processing of LEO-based GNSS TEC data from the perspective of real-time applications. 相似文献
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Discussion of GPS Anti-Jam Technology 总被引：4，自引：0，他引：4
The Global Positioning System (GPS) satellita navigation aiding system, sometimes called NAVSTAR, has become a utility to
the military and many civilian areas. GPS, currently consisting of 24 satellites, is used by the military for navigation,
precision weapons delivery, and the future digital battlefield. In the civilian sector, GPS is widely used as the primary
or secondary aid for land, water, and air navigation; as a surveying aid; as a vehicle location system; and as a precision
time standard for cellular and ATM sites. In the aviation community, GPS is becoming an integral part of the WAAS (Wide Area
Augmentation System) and the LAAS (Local Area Augmentation System) for en route navigation in North America and Category II
and III precision approach, and for surface navigation. The vulnerability of GPS have become the vulnerabilities of WAAS and
LAAS, and require consideration of interference mittigation techniques. ? 1999 John Wiley & Sons, Inc. 相似文献
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Patrick J. Fell 《Journal of Geodesy》1986,60(3):181-192
The Fourth International Geodetic Symposium on Satellite Positioning was held in Austin, Texas from 28 April to 2 May 1986.
The symposium was organized as a forum for the discussion of recent geodetic activities related to precise positioning using
observations from the Navy Navigation Satellite System (Transit) and the NAVSTAR Golbal Positioning System (GPS). In addition,
the sympsium promoted an exchange of ideas on the future direction of GPS geodetic activities and provided a summary of the
status, policy, and plans for both the GPS and Transit systems. This report summarizes the proceedings of the meeting. 相似文献
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The Global Positioning System (GPS) and Wide Area Augmentation System (WAAS) provide lower power signals that are susceptible
to interference. The potential exists for a person or organization to jam GPS or WAAS signals, causing a loss of service over
a large area. Accidental interence by extraneous radio transmissions on the GPS frequency also can cause loss of service.
Jamming has become a serious issue for GPS, and the U. S. military is making a significant effort to mitigate jamming effects.
While jamming is a major concern of the military, interference is of a no lesser concern to the civilian sector. In fact,
with varying emphasis both jamming and interference are concerns of the entire GPS user community. This article explores jamming
and interference threats to the GPS. We provide a general overview of the GPS signal structure, discuss jamming effects on
the GPS, and consider mitigating options. ? 1999 John Wiley & Sons, Inc. 相似文献
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We investigated a current numerical weather model, known as MAPS (Mesoscale Analysis and Prediction System), to determine
if it could precisely define the behavior of GPS signals in the tropospere, ultimately leading to improved GPS-determined
ellipsoidal heights. MAPS is the research version of the Rapid Update Cycle (RUC2) generated by NOAA's Forecast System Laboratory.
MAPS is generated on an hourly basis and provides coverage in the contiguous United States at a 40-km grid spacing. We processed
numerous subsets of GPS data collected over a months-long period on 23 static baselines ranging in length from 62 to 304 km.
The GPS data were processed in 1/2-hr, 1-hr, 2-hr, and 4-hr session lengths. The primary effort was to compare the precision
of heights obtained using a commonly adopted seasonal weather model with the precision of heights obtained using the MAPS
weather model. Our analysis shows that the current version of MAPS can lead to improvement in GPS height precision when session
lengths are shorter than two hours. For sessions longer than two hours, comparably precise heights may be obtained using a
less accurate seasonal model by introducing appropriate nuisance parameters into the height estimation process. ? 2001 John
Wiley & Sons, Inc. 相似文献
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GPS/INS navigation precision and its effect on airborne radio occultation retrieval accuracy 总被引：1，自引：1，他引：0
Paytsar Muradyan Jennifer S. Haase Feiqin Xie James L. Garrison Justin Voo 《GPS Solutions》2011,15(3):207-218
An airborne radio occultation (RO) system has been developed to retrieve atmospheric profiles of refractivity, moisture, and temperature. The long-term objective of such a system is deployment on commercial aircraft to increase the quantity of moisture observations in flight corridors in order to improve weather forecast accuracy. However, there are several factors important to operational feasibility that have an impact on the accuracy of the airborne RO results. We investigate the effects of different types of navigation system noise on the precision of the retrieved atmospheric profiles using recordings from the GNSS Instrument System for Multistatic and Occultation Sensing (GISMOS) test flights, which used an Applanix POS/AV 510 Global Positioning System (GPS)/Inertial Navigation System (INS). The data were processed using a carrier phase differential GPS technique, and then the GPS position and inertial measurement unit data were combined in a loosely coupled integrated inertial navigation solution. This study quantifies the velocity precision as a function of distance from GPS reference network sites, the velocity precision with or without an inertial measurement unit, the impact of the quality of the inertial measurement unit, and the compromise in precision resulting from the use of real-time autonomous GPS positioning. We find that using reference stations with baseline lengths of up to 760?km from the survey area has a negligible impact on the retrieved refractivity precision. We also find that only a small bias (less than 0.5% in refractivity) results from the use of an autonomous GPS solution rather than a post-processed differential solution when used in an integrated GPS/INS system. This greatly expands the potential range of an operational airborne radio occultation system, particularly over the oceans, where observations are sparse. 相似文献
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Larry Chesto 《GPS Solutions》2000,3(4):35-38
The forthcoming World Radiocommunication Conference (WRC) will deal with frequency allocation and protection issues that are
of fundamental importance to GNSS (Global Navigation Satellite System) and GPS (Global Positioning System), which is a component
of GNSS. In many countries, GPS L1 and L2 are not protected, and much needs to be done to obtain a frequency allocation for
GPS L5. A brief explanation of the International Telecommunication Union (ITU) and how it can impact satellite navigation
at its World Radiocommunication Conference in 2000 (WRC-2000) is provided. ? 2000 John Wiley & Sons, Inc. 相似文献
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We processed 30 consecutive days of Global Positioning System (GPS) data using the On-line Positioning Users Service (OPUS)
provided by the National Geodetic Survey (NGS) to determine how the accuracy of derived three-dimensional positional coordinates
depends on the length of the observing session T, for T ranging from 1 h to 4 h. We selected five Continuously Operating Reference Stations (CORS), distributed widely across the
USA, and processed the GPS data for each with corresponding data from three of its nearby CORS. Our results support the current
OPUS policy that recommends using a minimum of 2 h of static GPS data. In particular, 2 h of data yielded a root mean square
error of 0.8, 2.1, and 3.4 cm in the north, east, and up components of the derived positional coordinates, respectively. Results
drastically improve for solutions containing 3 h or more of GPS data. 相似文献
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近几年来,GPS/INS组合的导航系统——POS系统已逐步成熟,并应用于无人机飞控系统,虽然POS精度不是很高,但是其实现了影像外方位元素的直接获取,并且摆脱了传统摄影测量对大量地面控制点的严重依赖,方便了影像像控点的布设。同时,为了使成果DOM精度达到项目要求,少量控制点的布设仍不可避免,为此,如何合理选取困难地区像控点布设方案成为工程项目中急需解决的问题。为了获取针对困难地区的像控点合理布设方案,本文基于甘肃陇南地区土地确权项目,通过对测区无人机影像采用不同的像控点布设方案进行空三平差处理,分析正射影像图的平面精度情况来选取适合当地的布设方案。实验结果表明,在满足生产精度的前提下,适当放宽国家规范的像控点布设要求的同时,给出困难地形的像控点布设方案,能极大提高像控点测量野外作业效率,并且可以在其他测区推广使用。 相似文献